Attachment for blindstitching



1956 v. J. SIGODA 2,760,456

ATTACHMENT FOR BLINDSTITCHING Filed Feb. 9, 1952 2 Sheets-Sheet 1 INVENTOR. MC 70/? 1/ 5/600/1 DSTITCHING 2 Sheets-Sheet 2 Filed Feb. 9, 1952 INVENTOR. I40 70/? (AS76004 ATTORNzfY United rates 2,7sa,4ss

ATTACHMENT non nrmnsrrrcmo Application February 9, 1952, Serial No. 270,830

7 Claims. (Cl. 11214tl) This invention relates to attachments for sewing machines for blindstitching strip tape. By means of the disclosed device the raw edge of a garment may be bound to form a piped edge, a tubular piping (commonly known as spaghetti) having substantially concealed stitching may be formed without the necessity of inversion, and such spaghetti may be attached to the surface of garment materials to produce various pleasing ornamental eflects.

One feature of the invention resides in the fact that it may be attached to modern high speed sewing machines for economical production of such effects in a single sewing operation. The invention discloses the use of a novel folder or binder applied to any of the high speed sewing machines, being independent of the type of stitchfonning mechanism utilized.

In the high production manufacture of such articles special efforts must be made to eliminate difliculties arising from the high speed operation of the sewing machine. At lower speeds, the point of the needle follows a regular pattern as it is reciprocated. At high speeds, the point of the needle dances about in an erratic pattern. Such needle point deflections can be caused by changes in thread tension which may be due to an inherent defect in the thread tensioning devices when operated at high speeds or to small variations in the thickness of the needle thread, or by the varying resistance of the material to successive needle penetrations.

This becomes important when it is realized that materials commonly used in garment manufacture are between .005 to .010 of an inch in thickness and that it is necessary in the blindstitching operation for the needle thread to penetrate the material fibres edgewise sufliciently to hold the fabric in the sewn construction but Without passing through and appearing on the outer visible surface.

It is therefore a primary object of the invention to disclose means for precise positioning of certain insert blades over which the folded edges of the fabric strip are bent for the required needle penetration so that control over the point at which the needle pierces the fabric edgewise may be initially secured.

It is a further object to provide means to counteract the undesired needle point deflections occasioned by high speed operation.

The device as shown and described herein utilizes a binder or folder generally similar to the English type, adjustably mounted on the throat plate of the sewing machine in such position that the needle reciprocates in a path adjacent to and somewhat in advance of the fold inverting insert blades. These blades are of novel construction and arrangement and mark a major departure in binders of this type. As is usual in blindstitching, the folded strip edges are bent over an edge and inverted and presented so that the needle on each downward stroke passes into and out of the inner or hidden surface of the folded strip edges. In this device, the needle passes in this manner through both top and lower folds and the atent stitching is subsequently concealed within the sewn folds and therefore does not appear on the outer visible surfaces of either side of the sewn article.

While it has been customary to secure the English binder to the throat plate on the bed of the machine by means of a pair of screws passing through elongated slots in the tang of the binder, this permits only a relatively coarse adjustment of the position of the outlet of the folder laterally with respect to the needle. In the modifled binder of the invention, two independently adjustable insert blades, one aligned above the other, are provided, together with readily manipulatable means for lateral adjustment of such blades. Hence once such a binder is fixed in position as a whole on the bed of the machine, either blade may thereafter be separately adjusted as re quired for optimum positioning of its respective folded strip portion for proper needle penetration. This eliminates the necessity for resetting the binder as a whole, which is essentially a delicate matter. Such provision for precise adjustment of both blades independently makes possible the successful operation of the device at the high speeds required for modern high production requirements.

Certain materials occasion trouble in folders of this type due to the fact that they tend to cling to the needle shank, particularly when the needle is withdrawn from the work. This causes an uneven distribution of the folded edges of the top plies and due to the increased bulk in the folder, the needle point is deflected on the next downward stroke. This often causes improper stitching such as missed stitches and occasionally even damage to the needle point and needle breakage. It is therefore another purpose of the invention to provide means to counteract the floating of such materials by the use of a material clamping device operating in appropriately timed relationship to the normal feed action of the machine.

Other features and objects of the invention will appear from the detailed description which follows, taken in conjunction with the drawings, in which:

Fig. l is a perspective view of the attachment as a whole mounted on a modified throat plate which is partly broken away to show the modified feed dog, and in which the modified presser foot may also be seen;

Fig. 2 is a plan view showing the device as it would appear when attached to the bed of a standard high speed sewing machine, the arm and head of the machine being omitted for clarity;

Fig. 3 is a front elevation showing the attachment, the front wall of the folder being broken away;

Figs. 4, 5 and 6 are cross-sectional detail views taken respectively on lines 4-4, 5-5 and 6-6 of Fig. 3, with the front wall of the folder restored;

Fig. 7 is a front elevation partly in section, the folder being removed so that the means for mounting and laterally adjusting the insert blades may be seen;

Figs. 8 and 9 are plan views of the top and bottom insert blades, respectively;

Fig. 10 is detail perspective view taken at the outlet of the folder, showing how the folded edges of the fabric strip are bent over the forty-five degree edges of the blades and how the material clamp cooperates with the top blade to prevent floating of the folded strip during the stitching operation;

Fig. 11 is an enlarged detail view in perspective of the folded and sewn strip showing the folded edges as they are bent over the forty-five degree edges of the blades, the blades being omitted for clarity, and the successive stitches which result in the formation of the completed tubing or spaghetti;

Fig. 12a is a cross-section of the tubing taken on line 12-12 of Fig. 11, and

Fig. 12b is a similar cross-section showing how the piping would look with an insert as in binding off the raw edge of a garment material.

The usual throat plate of the sewing machine is replaced by a throat plate of tapering thickness (see Figs. 1 and 2.) so that the folder portion of the attachment may be inclined at an angle which facilitates operation. Throat plate 10 has a centrally located recess 11 in which the attachment is accommodated, the usual feeder slots 12 for feed dog 13 and the usual countersunk holes by which it may be secured by screws 14 to the sewing machine bed.

The attachment has a tang 15 by which it may be suitably secured to throat plate It) as by means of screw 16 and dowel pins 17. Tang 15 extends from a vertically disposed rectangular block 2% which is the backbone of the attachment. a

Folder 30 is attached to a plate 30:: which is mounted on front vertical surface 21 of block by screws 31 whichmay pass through elongated slots for lateral adjustment of the folder as a whole with respect to the needle. In this embodiment, folder is fixed on block 20 by dowel pins 32, screws 31 merely holding the folder in a selected position on front surface 21.

Folder 30 is of the usual English binder construction, being appropriately channelled and bent so that the lengthwise edges of the fabric strip will be curled up first into a U shape, and then progressively into a W shape (see Figs. 4 and 5), and finally, in the vicinity of the needle action as it is bent and turned over a forty-five degree edge, into reversed U shape. Between the arms of this reversed U shape it is customary to insert the raw edge of a garment material for binding. However, with this device, if the insert material is omitted, the folded over strip can be readily formed into a continuous tubing or spaghetti (see Fig. 11) without the necessity of the usual subsequent inversion, as will be more fully described.

To assist in this folding action, rib 33 rises along the horizontal centerline of the folder channel gradually from the inner vertical surface 34 at inlet 35 of the folder until it is a well defined convex-shaped separator at the outlet 36. The manner in which the outer walls of the folder follow and supplement this configuration is best shown in the cross-sectional views Figs. 4, 5 and 6. To turn the folded edges of the strip at the outlet of the folder, the usual English binder employs a fixed, concave-shaped nose disposed at a forty-five degree angle at the outlet end of rib 33. In this device, this nose is replaced by a spaced pair of laterally adjustable blades and 41 which are slidably mounted in longitudinal grooves 22 and 23 respectively of block 20.

At their forward oflset ends, these blades are placed on either side of the outlet end of rib 33, one above the other. Each blade has a notch 42 which is made up of an edge 43 which is disposed at a forty-five degree angfle to the longitudinal axis of the blade and an edge 44 which is at right angles to this axis. The folded strip edges are bent and turned over edge 43 of each blade and are restrained from leaving the vicinity of the needle action by edge 44.

As previously indicated, the penetration of the folded plies is a delicate matter and in order to locate the folded strip edges properly for this purpose, means for separately positioning edges 43 of blades 40 and 41 is provided. This positioning as can readily be appreciated, is critical because of the erratic needle point vibration at high rates of reciprocation, and While this can be counteracted or dampened, the initial location of edges 43 is of the utmost importance.

To accomplish this initial positioning, each of blades 40 and 41 is provided with an opening having a straight edge 45 joining an arcuate edge 46, and a second clearance opening 47 spaced therefrom. A pair of laterally spaced, adjustable thumbscrews 24 and 25, each of which has a tapering, conical point 26, are threaded into vertically disposed, parallel bores in block 20 which are in. intersecting relation to grooves 22 and 23. One inclined side of conical point 26 of thumbscrew 24 is in register with straight edge 45 of upper blade 40. Hole 47 in lower blade 41 allows clearance for the projecting conical tip 26 of screw 24 so that blade 41 is not affected by adjustment of thumbscrew 24. In like manner, thumbscrew 25 passes through clearance hole 47 in upper blade 40 without affecting it. It will be seen that the inclined side of conical point 26 of thumbscrew 25 in engagement with the straight edge 45 of lower blade 41 provides the required lateral adjustment thereof in like manner.

Downward manipulation of thumbscrew 24 will cause top blade 44) to shift toward the needle and corresponding manipulation of thumbscrew 25 will have the same effect on lower blade 41.

While the pressure exerted by the folded strip in passing over edges 43 would be enough to cause blades 40 and 41 to be shifted away from the needle on upward manipulation of the thumbscrews, it is preferred to provide additional spring means to assist in withdrawing each of the blades from the needle vicinity when the appropriate thumbscrew is adjusted upwardly. On one end of block 20, two leaf springs 27 and 28 are anchored by screw 29. The lower end of leaf spring 27 engages slot 48 in upper blade 40 and the lower end of leaf spring 28 engages a similar slot 48 in lower blade 41. Each blade is therefore under separate, independent tension.

As there is some vibration present when most machines are operated, it is desirable to provide means for retaining the thumbscrews in their adjusted positions. A spring detent 49 having arms 50 and 51, each of which has a long vertical dimple adapted to coact with the serrations of the vertical knurling on the head of each of the thumbscrews, eifectively prevents unintentional rotation thereof.

To counteract the erratic pattern followed by the point of the needle at high rates of reciprocation, it is found desirable to provide a needle guide tube 52 vertically disposed in the outlet end of folder 30 in line with and above the usual needle hole. It is well known that for any given cross-section, a needle of short length is stiffer than a long needle and accordingly is much more diflicult to deflect from the desired path of reciprocation. The effect of needle guide tube 52 at the position indicated is to lower the effective point of support of the needle so that only that portion of the needle projecting below the bottom of needle guide tube 52 is free to vibrate, thus dampening undesired deflections, and the needle point therefore tends to enter the fibres accurately after edges 43 of the blades 40 and 41 are properly set. Since the needle point enters the fabric fibres immediately below the end of guide 52, there is a further dampening of undesired needle point deflection and vibration as the fibres of the work tend to hold the needle against edges 43.

As mentioned previously, certain very thin or slack bodied materials tend to float with the needle on withdrawal from the work. Normally, the usual presser foot counteracts this tendency to float but in an arrangement such as this where there is insufficient room for the usual presser foot, a suitably modified presser foot 19 as shown in Fig. 1, must be provided. Such a foot is not effective to counteract this tendency and some auxiliary material clamping means must be provided.

Stud 55 mounted on the rear vertical face of block 20 supports a pivotally mounted arm 56 which extends lengthwise along the rear face of block 20 toward the needle. Arm 56 has an elbow 57 which extends parallel to the line of feed to a point closely adjacent the needle guide tube 52. Elbow 57 has a downward extension 58 which is in register with an opening 59 in folder 30 at the outlet end thereof so that the end of extension 58 may press upon the folded strip plies as they rest on the top of blade 40 (see Fig. 10). Suitable resilient tension is exerted on these plies by means of a compression spring 63 pressing on extension 64 of pivoted arm 56 through a spacer bushing 65.

Adjustment of tension to accommodate the paraeeonse ticular thickness of the strip, the number of folded plies and the slipperiness of the fabric is made by suitable manipulation of thumbscrew 66.

It is necessary that arm 5'6 be operated in such sequence that end 58 is raised to allow the folded strip to be pulled through folder 30 when the feed action of the machine is effective, and that it be clamped down on the infolded strip until the needle 18 completes its penetration and withdrawal, thus anchoring the folded strip at that point and preventing floating and also tending to minimize needle deflection.

This may be accomplished by operating arm 56 from any part of the sewing machine which will cause it to raise during the rearward feed stroke and to lower onto the folded strip at all other times. It is possible to obtain this lift motion either from some suitable portion of the feed dog or from the needle bar, and in this case, the latter method is shown.

An upwardly extending arm 60 connected to elbow 57 is suitably bent (see Fig. 3) so that it may be engaged by a rearwardly extending pin 61 which is clamped 62 to the needle bar. The position of clamp 62 is adjusted on the needle bar so that when the needle is at the upper end of its stroke, arm 60 is shifted laterally by pin 61, thus raising the lower end of downward extension 53 from the top surface of blade 40. The folded plies then can pass over the surface of blade 46 under the influence of the feed action of the sewing machine. Spring 63 returns extension 58 to the clamp position whenever the needle leaves the upper end of its stroke.

The operation of the device in conjunction with the sewing machine may be readily understood. A reel of binding strip is mounted in the vicinity of the machine and the end of the strip is fed into the inlet of folder 3!) and drawn through to the outlet 36. The longitudinal slot shown in Fig. 1 is for the purpose of using some thin member to assist in drawing the strip through the folder channel initially. At the outlet, the folded over edges of the strip are passed between the inner facing surfaces of blades 40 and 41 over edges 43, and drawn under the needle parallel to the line of feed. If an insert is to be bound, it is placed within the folded over edges and the stitching is begun.

If the needle does not nip either the top or bottom plies properly, the appropriate thumbscrew is adjusted downwardly until the needle point penetrates the ply sufficiently. If the needle thread shows through the outer surface on either top or bottom, the appropriate thumbscrew is adjusted upwardly.

The formation of the tubing can best be understood by referring to Fig. ll. At the right side, the folded strip is seen in a distorted cross-section which roughly corresponds to that shown in Fig. 5. The needle 18 nips the inner side of the folded edge at A, passes through the fibres of the material lengthwise and emerges at B. The lower fold is spaced a short distance below and the needle point enters this lower fold at C, again passes lengthwise through the fibres of the material and emerges at D. The needle thread loop formed below D is entered by the hook, if the machine is a lock-stitch type, and the lower bobbin thread is entwined in the needle thread loop. On withdrawal of the needle upwardly through penetrations D and C, the bobbin thread is carried upwardly to a point between C and B, and the needle thread is withdrawn through penetrations B and A. During this, clamp extension 58 is resting on the top folds under the tension of spring 53, holding the strip against the top surface of blade 41). As the needle reaches the upper part of its stroke, clamp extension 58 is released, and the feed then being efiective, the sewn tubing is drawn past the needle rearwardly. As the tubing moves rearwardly the loose needle and bobbin threads are progressively tightened up. As shown at the left in Fig. 11, the top 6 and bottom lines of stitching lie so close to each other that the normal pulling out of the tubing as it returns to cylindrical shape conceals the lines of stitching adjacent the seam, as can best be appreciated in Figs. 12a and 1212.

In view of this substantial concealment of the stitching, a tubing can be formed in one operation, without inversion, at high speed.

Such spaghetti can be used as is for loops, etc., or may be subsequently applied to garments in any of the usual ways. it may also be sewn directly on the surface of the garment material as it is formed by appropriate modification of folder 3% so that the garment material instead of being inserted between the folds is placed beneath the folds between the bottom of lower blade ii and the needle or throat plate, as is well known in the art.

While the present preferred embodiment has been described in detail for the purpose of illustration, it is to be understood that the invention is not limited to the details of the construction shown and described, but is to be construed broadly within the spirit and scope of the appended claims.

What is claimed, is:

1. An attachment for sewing machines for blindstitching both edges of a continuous fabric strip into a tubular member in one operation, comprising a channelled fabric strip folder mounted on the needle plate with its outlet adapted to be positioned adjacent the vertical path of the needle, said folder being constructed and arranged so that longitudinal folds are produced in each edge of said strip as it is drawn through said folder to the needle, said folder having a pair of vertically spaced superposed longitudinal slots, and a pair of blades adjustably mounted in said slots having ends adjacent the outlet of said folder, each of said blade ends having a transverse edge over which its respective fabric fold is bent to be turned as it emerges from the folder outlet and over which said turned fold is presented to the needle for controlled nipping of the outermost ply so that successive passage of the needle through both folds produces a blindstitched tubular member, and means for separately and independently shifting each of said blades to and from the needle path comprising a pair of manipulata'ole thumbscrews vertically threaded into said folder, each of said thumbscrews having a conical, tapering point, the sloping side of which engages a portion of one of said blades so that manipulation of its thumbscrew causes each blade to be shifted laterally.

2. The device defined in claim 1 in which separate resilient members are provided each of which continuously urges one of said blades into contact with the sloping side of the conical point of its respective mating thumbscrew.

3. An attachment for sewing machines for blindstitching both edges of a continuous fabric strip into a tubular member in one operation, comprising a channelled fabric strip folder mounted on the needle plate with its outlet adapted to be positioned adjacent the vertical path of the needle, said folder being constructed and arranged so that longitudinal folds are produced in each edge of said strip as it is drawn through said folder to the needle, and a pair of vertically spaced, superposed blades horizontally disposed in said folder having their ends adjacent the outlet of said folder, each of said blade ends having one portion with an angularly disposed edge over which its respective fabric fold is bent to be turned as it emerges from the folder and over which said turned fold is presented to the needle for controlled nipping of the outermost ply and a second portion having an edge angularly disposed to the first mentioned edge to retain said turned fold in position over said first mentioned edge for nipping by the needle.

4. An attachment for sewing machines for blindstitching both edges of a continuous fabric strip into a tubular member in one operation, comprising a channelled fabric strip folder mounted on the needle plate with its outlet adapted to be positioned adjacent the vertical path of the needle, said folder being constructed and arranged so that longitudinal folds are produced in each edge of said fabric strip as it is drawn through said folder to the needle, a pair of vertically spaced, superposed blades horizontally disposed in said folder having their ends adjacent the outlet of said folder, each of said blade ends having an angularly disposed edge over which its respective fabric fold is bent to be turned as it emerges from folder outlet and over which said turned fold is presented to the needle for controlled nipping of the outermost ply,

means for separately and independently shifting each of said blades laterally with respect to the needle path comprising a pair of manipulatable thumbscrews vertically threaded into said folder each of which has a conical, tapering point, the sloping side of which engages a portion of one of said blades so that manipulation of its thumbscrew causes each blade to be shifted laterally, and spring members in engagement with each of said thumbscrews to prevent unintentional rotation thereof.

5. An attachment for sewing machines for blindstitching both edges of a continuous fabric strip into a tubular member in one operation, comprising a channelled fabric strip folder mounted on the needle plate with its outlet adapted to be positioned adjacent the vertical path of the needle, said folder being constructed and arranged so that longitudinal folds are produced in each edge of said strip as it is drawn through said folder to the needle, a pair of vertically spaced, superposed blades horizontally disposed in said folder having their ends adjacent the outlet of said folder, each of said blade ends having an angularly disposed edge over which its respective fabric fold is bent to be turned as it emerges from the folder outlet and over which said turned fold is presented to the needle for controlled nipping of the outermost ply, and a needle guide member mounted on an extension of said folder above the angular edge of each of said blades in line with the needle hole.

6. An attachment for sewing machines for blindstitching both edges of a continuous fabric strip into a tubular member in one operation, comprising a channelled fabric strip folder mounted on the needle plate with its outlet adapted to be positioned adjacent the vertical path of the needle, said folder being constructed and arranged so that longitudinal folds are produced in each edge of said strip as it is drawn through said folder to the needle, a pair of vertically spaced, superposed blades horizontally disposed in said folder having their ends adjacent the outlet of said folder, each of said blade ends having an angularly disposed edge over which its respective fabric fold is bent to be turned as it emerges from the folder outlet and over which, said turned fold is presented to the needle for controlled nipping of the outermost ply, an arm pivotally mounted on said folder, said arm having a vertically depending extension arranged to be held in contact with the topmost folded edge of the fabric strip to clamp it against the top surface of the topmost blade during the stitching operation to restrain said strip from movement during needle penetration, means for normally holding said extension in contact with said fabric fold, and means actuated during the rearward feed movement to raise said extension out of contact with said fabric fold.

7. An attachment for sewing machines for blindstitching both edges of a continuous fabric strip into a tubular member in one operation, comprising a channelled fabric strip folder mounted on the needle plate with its outlet adapted to be positioned adjacent the vertical path of the needle, said folder being constructed and arranged so that longitudinal folds are produced in each edge of said strip as it is drawn through said folder to the needle, a pair of vertically spaced, superposed blades horizontally disposed in said folder having their ends adjacent the outlet of said folder, each of said blade ends having an angularly disposed edge over which its respective fabric fold is bent to beturned as it emergies from the folder outlet and over which said turned fold is presented to the needle for controlled nipping of the outermost ply, an arm pivotally mounted on said folder, said arm having a vertically depending extension arranged to be held in contact with the topmost folded edge of the fabric strip to clamp it against the top surface of the topmost blade during the stitching operation to restrain said strip from movement during needle penetration, spring means for normally holding said extension in contact with said fabric fold, and a member connected with the needle bar actuated during the rearward feed movement to raise said extension out of contact with said fabric fold when the needle bar is at a certain portion of its stroke.

References Cited in the file of this patent UNITED STATES PATENTS 220,779 Wemple Oct. 21, 1879 653,322 Strong July 10, 1900 794,690 Steward July 11, 1905 1,163,220 Corey Dec. 7, 1915 1,393,498 Chalman Oct. 11, 1921 2,136,288 Ebert Nov. 8, 1938 

